1. Field of the Invention
The present invention relates generally to a sun visor for automotive vehicle and more specifically to an improved hinge structure for same.
2. Description of the Prior Art
In a previously proposed arrangement such as shown in FIGS. 1 and 2 of the drawings, a sun visor 1 has been hingedly mounted on the ceiling 6 of a vehicle cabin via an angled shaft 2 and a springy envelope 3 which engages the surface of the shaft 2. Fixedly connected to the springy envelope 3 is a wire frame 4 on which the padding and cover 5 (shown in phantom) are disposed. In operation this arrangement may be set in any given desired position so as to adequately block out the rays of the sun while not excessively obscuring the driver's view. However, this arrangement, particularly after prolonged use has suffered from the drawback of moving from the selected position under the influence of vehicle vibration and the like. This has been particularly prevalent when the visor is set in a non-use or "storage" position wherein it abuts the ceiling 6 of the vehicle cabin. Hence, the driver and/or passengers of the vehicle have been plagued with the constant need to manually move the visor back to its storage position, sometimes with annoying frequency.
To overcome this problem it has been subsequently proposed to provide a hinge arrangement having a "snap action" which securely holds the visor in either one of two diametrically opposed positions. This arrangement is shown in FIGS. 3, 4 and 5A-5C. As best seen in the exploded view of FIG. 4, this arrangement comprises a shaft 7 having flats 8 formed on either side thereof, an envelope 9 which is adapted to slidably receive the shaft 7 therein and which is disposed about the shaft, and a leaf spring 10 which is adapted to seat on top of the envelope 9 and engage the shaft 7 through apertures 11 formed in either side of the envelope. The leaf spring is secured in place by a clip 12 which fits up around the bottom of the envelope and which includes apertures 13 into which barb-like extensions 14 extending from the leaf spring, engage.
However, this arrangement has suffered from a drawback in that, as will be understood from FIGS. 5A to 5C, as the envelope 9 is rotated about the shaft 7 from a position such as that shown in FIG. 5A to one shown in FIG. 5B, the force of the leaf spring 10 tends, due to the presence of the two flats 8, to automatically force the envelope 9 to continue to rotate until the position illustrated in FIG. 5C is reached. Thus, while the arrangement has served adequately to retain the visor in the storage position without trouble, once the visor is rotated toward the windshield 15 of the vehicle to the degree of entering the range indicated by the arrow "a" in FIG. 3, then irrespective of the operators wish, the visor will snap to a position diametrically opposite that of the storage one. This is of course undesirable as the driver (or passenger) may require an orientation which falls within the aforementioned range but wherein the snap action will tend to be induced.
To solve this, it has been proposed to provide only a single flat 16 on the shaft and a single surface 17 on the leaf spring 18 for engaging the flat (See FIGS. 6A-6C). Now, while this has provided only a single zone in which a desirable "snap" toward and into the storage position is provided, the arrangement has suffered from very jerky rotation of the visor from the storage position and tended to lack sufficient position maintaining ability. The reason for the jerky rotation is due to the existence of only one flat on the shaft and the resulting "bulging out" of only one side of the leaf spring 18 (as occurs as the envelope is rotated from the position shown in FIG. 6C to that in FIG. 6B. This "one sided bulging" action tends to produce a force which acts about a fulcrum point located in the region of the parallel leg portions 19 of the leaf spring and generates a moment which tends to force the leaf spring to a position eccentric with respect to the envelope. Further, as only one flat is inducing a "bulging" of the leaf spring the resulting force forcing the surface of the leaf spring clip and shaft into friction generating contact is diminished as compared with the dual flat arrangement.